Pushbutton using three stage unitary spring as a contactor means



April 23, 1968 F. J. WEREMEY ING PUSHBUTTON USING THREE STAGE UNITARY SPR AS A CONTACTOR MEANS Filed Feb. 9, 1966 United States Patent 3,379,851 PUSHBUTTON USING THREE STAGE UNITARY SPRING AS A CONTACTOR MEANS Frederick J. Weremey, Mattapan, Mass., assignor to United-Carr Incorporated, Boston, Mass., a corporation of Delaware Filed Feb. 9, 1966, Ser. No. 526,255 1 Claim. (Cl. 200-159) ABSTRACT OF THE DISCLOSURE A pushbutton switch is disclosed to provide switching means wherein a unitary stepped spring is utilized as a contact and also to mechanically return the plunger to the normally open position.

This invention relates generally to switches and more specifically to a switch utilizing a stepped-spring.

An object of the present invention is to provide a simple inexpensive construction of a normally open switch.

Another object of the present invention is to utilize a stepped-spring as a contact as well as providing means of mechanically returning the plunger to a rest position.

The prior art indicates that mechanical switches of the normally open type utilize separate contact means and use the spring member only for mechanical purposes. This required not only separate contact means but structure to hold the contact means in engagement with the spring member. In the present invention the use .of a steppedspring provides an element which can be utilized as an electric contact portion in a switch which, for example, is connected directly to ground.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

In the drawing:

FIG. 1 is a side elevation of the switch;

FIG. 2 is a section taken on line 22 of FIG. 1; and

FIG. 3 is a bottom plan view .of the switch shown in FIG. 2.

In the drawing, there is shown a switch comprising a housing 12 formed of an electrically conductive material such as steel, :a plunger 14, a stepped compression spring 16, an insulating retainer member 18 and a terminal 20.

The housing 12 includes a body portion 22 generally tubular in configuration, open at first and second ends. A tubular extension 24 having an axial core 26 formed at the first end of the body portion 22. The axis of the core 26 is aligned as a continuation of the cavity of the body portion 22. The cavity formed in the upper portion of the body portion 22 is of greater diameter than the core 26 thereby providing an internal circumferential shoulder 28. This upper portion may conveniently be referred to as the upper chamber 30 of the body portion 22. An internal circumferential step 32 forms a second internal shoulder in the body portion 22 in close proximity to the upper chamber 30 and spaced from the shoulder 28. The remaining portion of the body portion 22 has a cavity of larger diameter than the upper chamber 30 to provide a lower chamber 34.

The plunger 1-4 comprises a cylindrical upper portion rounded at one terminal end and having a spring engagement portion 36 extending from the other end, of larger external diameter than the cylindrical upper portion, providing a plunger shoulder 38. An axial core may be formed in the spring engagement portion 36 extending from its free terminal end.

The unitary stepped-spring 16 is helical in configuration and has three portions, an upper increment 40 which defines an external diameter, approximately equal to the diameter of the chamber 30, an intermediate increment 42 3,379,851 Patented Apr. 23, 1968 of smaller diameter than the upper increment 40 and a lower increment 44 of smaller diameter than the intermediate increment 42.

The insulating retainer 18 is formed of an insulating material and comprises a tubular component open at both ends. The insulating retainer 18 has an external diameter approximately equal to the diameter of the lower cham ber 34 and has an internal diameter slightly greater than the external diameter of the increment 42 of the spring 16.

To assemble the switch 10 the plunger 14 is passed into the housing 12 until the plungers shoulder 38 butts against the internal shoulder 28 of the upper chamber 30. A portion of the plunger will extend up through the tubular extension 24 and beyond the tubular extension 24 as shown in FIG. 1. The stepped-spring 16 is now dropped into the housing with the upper increment 40 abutting against the internal shoulder 28 and circumscribing a portion of the spring engagement portion 36. The intermediate increment 42 circumscribes the spring engagement portion 36 of the plunger 14 and is spaced slightly therefrom and the lower increment 44 abuts against the free end of the spring engagement portion 3 6 and extends well down into the lower chamber 34. for a predetermined distance. The terminal 20 is formed of a conductive material.

The terminal 20 is inserted into the insulating retainer 18 which is upset to secure it thereto. Then, the subassembly consisting of the terminal 20 and the retainer member 18 is dropped into the housing 12 and pressed against the internal step 32 thereby compressing the upper portion 40 of the spring 16 between the upper surface of the retainer member 18 and the shoulder 28. While maintaining this pressure the lower portion of the housing 12 is curled circumferentially around the lower stepped portion of the insulating retainer 18 thereby securing it and completing the assembly. The major portion of the terminal 20 extends beyond the area defined by the housing 12 as shown in FIG. 2. The terminal 20 is spaced from the spring 16.

The operation of the assembled switch is rather simple, if axial pressure is now applied to the plunger, the intermediate increment 42 of the spring will be extended or stretched while the lower increment 44 will be moved toward the terminal 20. Once the lower increment 44 engages against the terminal 20 it will be placed under compression which will continue up to the limits of a provided over-carry. If the plunger should now be released the compressed lower increment 44 would drive the plunger away from the terminal 20 and the extended intermediate increment 44 would compress to its original configuration thereby returning the switch to its normally open position.

If desired, the plunger 14 may include a protuberance which extends at right angles from its external wall and this protuberance may slide within an axial groove formed in the tubular extension 24 for predetermined distance and then by rotating the plunger 14 in either a clockwise or counterclockwise direction it may slip into a second channel formed at right angles to the first channel thereby stopping the plunger so that the axial force may be removed and yet the engagement between the lower increment 44- and the terminal 20 be maintained until the plunger is rotated in another direction to place it Within the axial groove and thereby on release allow the expanded forces of the intermediate increment 42 to return it to its original configuration thereby returning the switch to its normally open position.

With reference to the foregoing description it is to be understood that what has been disclosed herein represents only a single embodiment of the invention and is to be construed as illustrative rather than restrictive in nature and that the invention is best described by the following claim.

What is claimed is:

1. A switch comprising a housing, said housing being opened at both ends, and having an axial cavity formed therethrough, a plunger fitted within said housing, having a lower terminal end being axially movable in relation to said housing, a spring lying within said axial cavity, having an upper increment circumscribing a portion of said plunger and butted against an upper shoulder and said housing having a lower internal circumferential step, an intermediate increment having a smaller external diameter than said upper increment and circumscribing a portion of said plunger and a lower increment of smaller diameter than the intermediate increment and being in engaged relationship to said lower terminal end of said plunger and having a free terminal end spaced from all elements of said housing, an insulating retainer member having a portion thereof within said axial cavity, having an upper edge butting said upper increment and having a lower edge engaging a terminal, and the length of said spring increment being such that the pressure of said plunger will place the lower increment under compression and the intermediate increment under tension.

References Cited UNITED STATES PATENTS 595,963 12/1897 McCaughey 200159 2,444,552 7/1948 Brantingson 200--159 2,523,125 9/1950 Ley 200169 2,907,852 10/1959 Lon-g et al 200-159 FOREIGN PATENTS 30,310 7/ 1964 Germany.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

